Lay-in lugs are provided in many electrical products as the means to electrically connect service or feed phase/neutral conductors to electrical metering equipment and/or circuit protection. All lay-in lug assemblies contain a lug body, a tapped plate (referred to as the nut plate) and a wire binding screw. During a typical installation with lay-in lug assemblies, the wire binding screw and the nut plate are removed by sliding out the nut plate prior to installing a phase/neutral conductor. Sliding-out the wire binding screw and nut plate provides top down access to the lug body. This simplifies the installation of a phase/neutral conductor to the lug body. Once the phase/neutral conductor has been installed the nut plate is slide-in and the wire binding screw is driven to the necessary torque requirements.
There are at least two types of nut plates used today in lay-in lug assemblies. Extruded-punched and formed plates are known to be used in existing applications. If the nut plate is of the extruded type, then the nut plate would only need to be secured in the direction of assembly (front to back with respect to the lug body). This means an additional bi-directional restraint is needed. In the extruded case, the nut plate, by default, would be constrained from top to bottom with respect to the lug body.
Currently, securing the nut plate to the lug body or limiting the nut plate's slide-out motion is achieved by driving the wire binding screw into the nut plate far enough such that the screw enters the wire way of the lug body and creates pressure that keeps the nut plate in place. The nut plate retention in the assembly is dependent on the location and torque of the wire binding screw. One problem with this method is that if the screw is not properly assembled the nut plate and screw sometimes falls out during transit or during installation of the enclosure. This increases the chances for the nut plate to be misplaced, lost, or in some cases fall in unreachable places. When this happens replacement parts must be shipped or in extreme cases, finished goods replaced. This is a costly and timely burden for the manufacturer and distributor, as well as, an aggravation for the customer.
This invention improves on the deficiencies of the prior art and provides an inventive lay-in lug assembly nut plate retainer.